People of the Tenderloin window-shopping along Eddy Street in San Francisco might be surprised to look into the Lower Branch Gallery and see their own faces looking back at them.

They are there, in picture frames, because an amateur snapshot photographer named Troy Holden persuaded them to sit for a portrait in their home or workplace. That took a year of canvassing just to get 50 willing subjects to form the exhibition "Neighbors."

It's a short exhibition - 10 hours of hanging will yield just six days of viewing. And the poster-size prints are squeezed frame to frame in a shoe box of a gallery.

"It's going to be dense, but I like that because this neighborhood is dense," says Holden, while drinking a Modelo tall during an installation break. "A small gallery full of big photos."

This is the first solo show for Holden, who is 38 and lives in Bernal Heights with his wife and 2-year-old daughter. But he is not a Tenderloin tourist. The neighborhood found him the day he arrived by Greyhound from Michigan, in 1996.

He was walking around when someone tossed a television set out a third-floor window. It wasn't the act itself that impressed him. It was that nobody seemed bothered by it, as if it were just another way to turn it off.

"I thought, 'OK,' " he says. " 'I'm home.' "

He lived next to the Market Street Cinema, between Sixth and Seventh, long before the term "Mid-Market" made it marketable. Then he moved to Los Angeles and hated it so much that he celebrated his 26th birthday by having the Giants "SF" logo tattooed on the inside of each forearm. He was back after a year, to the day, and found his way to the right gallery.

Gritty gallery

Lower Branch, named for its lowbrow street-art aspirations, is painted like a Giants home uniform, cream with orange stripes. Open for a year, the gallery used to be an adult bookstore, and that is how Holden remembers it, not for the merchandise but for the location. He walked his dog all over the Tenderloin but never took a picture until he bought a Dell desktop computer, which happened to come with a Canon Elph, a trendy perk at the time.

He started taking quick-draw snapshots and posting them on Flickr, where he was discovered by Dina Hilliard, executive director of the North of Market/Tenderloin Community Benefit District.

"He captured the beautiful grittiness of his subjects very nicely," she says.

Her suggestion was to set up a formal portrait studio with a white tarp, lighting and backdrop, then open it for a one-day shoot. His suggestion was make "environmental portraits," shooting people in their home or workplace exactly as he found them. His only criterion was that they not clean the place before he got there.

The grant was $2,000 (to cover printing costs), and terms were that he could only shoot residents of the Tenderloin, Mid-Market and SoMa neighborhoods. He used his own handheld digital with a wide-angle lens and whatever light came through the window, if there was one. The only assistance he had was a translator for three Russian couples.

This is Holden's first art commission, and he was not paid, thus preserving his amateur status. Professionally, he's been a bartender, a cabbie and a coffee barista, and now works in customer service.

"The photography I do in my spare time, obsessively," he says, "before work, after work, at lunch and on weekends."

To find his subjects, he hung signs in SROs and residential hotels, leaving his phone number and e-mail address. In most cases, he'd never met the subject before he arrived for the shoot.

"It was an awkward situation, but I tried to find a bond with them to get them to relax," he says. "I put myself in an uncomfortable situation making these portraits and trying to do them well."

Subjects got prints

At the end of the project, Holden delivered a framed and matted print to each of his subjects, 8 by 10, which is about one-quarter the size of the photographs in the gallery. Some of the subjects took their print and that was the end of it. Some of the subjects invited him back.

"I'd like to make annual portraits of these people," he says. "Ultimately I'd like to build an archive of 30 or 40 years of the city and the people who live here."

The show at Lower Branch closes Wednesday but he's already looking for a place to reopen "Neighbors," maybe for longer than six days.